Abstract Objectives Hypoglycemia is a limiting factor in the achievement of strict glycemic control. The primary objective of this 9-week study was to determine the frequency of hypoglycemia in patients with stable insulin-treated type 2 diabetes mellitus by comparing self-monitored blood glucose (SMBG) measurement with continuous glucose monitoring (CGM). Methods This was an observational prospective study. Included in the study were 63 stable, insulin-treated patients with type 2 diabetes. They were instructed to record 2 daily capillary blood glucose readings, pre- and/or postprandial, in a sequential way during 8 consecutive weeks. A CGM system was worn during an additional week. We evaluated the frequency of hypoglycemia using the 8-week SMBG profile and the 1 CGM week. Results SMBG revealed that 50% of the patients had experienced hypoglycemia. CGM found hypoglycemia in 59% of patients. Significantly higher percentages of hyperglycemic and hypoglycemic episodes were detected by CGM than by capillary blood glucose measurements (61.1% vs. 50.8%; p=0.047) and (3.8% vs. 1.7%; p=0.016); 33% of patients experienced nocturnal hypoglycemia, and 19% of patients who had no data concerning hypoglycemia recorded in the capillary blood glucose diary had experienced hypoglycemia as measured by CGM, and the hypoglycemia occurred mainly during the nocturnal period. Conclusions In stable well-controlled, insulin-treated patients with type 2 diabetes, CGM showed higher numbers of hypoglycemic events than did SMBG, especially at night. CGM is a useful tool that provides clinically valuable information about glucose control in these patients.